INTERNET-DRAFT Danny McPherson
Arbor Networks
Naiming Shen
Cisco Systems
Expires: March 2008 September 30, 2007
Intended Status: Proposed Standard
Dynamic Hostname Exchange Mechanism for IS-IS
<draft-ietf-isis-rfc2763bis-00.txt>
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Copyright (C) The IETF Trust (2007).
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Abstract
Currently, there does not exist a simple and dynamic mechanism for
routers running IS-IS to learn about symbolic hostnames. This
document defines a new TLV which allows the IS-IS routers to flood
their name-to-systemID mapping information across the IS-IS network.
The intention of this document is to provide an update to [RFC 2763].
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Specification of Requirements . . . . . . . . . . . . . . . 4
2. Possible Solutions . . . . . . . . . . . . . . . . . . . . . . 4
3. Dynamic Hostname TLV . . . . . . . . . . . . . . . . . . . . . 5
4. Implementation . . . . . . . . . . . . . . . . . . . . . . . . 6
5. Security Considerations. . . . . . . . . . . . . . . . . . . . 6
6. Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . 6
7. IANA Considerations. . . . . . . . . . . . . . . . . . . . . . 7
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8
8.1. Normative References. . . . . . . . . . . . . . . . . . . . 8
8.2. Informative References. . . . . . . . . . . . . . . . . . . 8
9. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 8
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1. Introduction
IS-IS uses a variable 1-8 byte system ID (normally 6 bytes) to
represent a node in the network. For management and operation
reasons, network operators need to check the status of IS-IS
adjacencies, entries in the routing table and the content of the IS-
IS link state database. It is obvious that, when looking at
diagnostics information, hexadecimal representations of systemIDs and
LSP identifiers are less clear than symbolic names.
One way to overcome this problem is to define a name-to-systemID
mapping on a router. This mapping can be used bidirectionally. E.g.,
to find symbolic names for systemIDs, and to find systemIDs for
symbolic names. One way to build this table of mappings is by static
definitions. Among network administrators who use IS-IS as their IGP
it is current practice to define such static mappings.
Thus every router has to maintain a statically configured table with
mappings between router names and systemIDs. These tables need to
contain all names and systemIDs of all routers in the network, and
must be modified each time an addition, deletion or change occurs..
There are several ways one could build such a table. One is via
static configurations. Another scheme that could be implemented is
via DNS lookups. In this document we propose a third solution. We
hope the proposed solution is easier and more manageable than static
mapping or DNS schemes, and wide-scale implementation and deployment
of this capability has proved this to be the case.
1.1. Specification of Requirements
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC 2119].
2. Possible Solutions
The obvious drawback of static configuration of mappings is the issue
of scalability and maintainability. The network operators have to
maintain the name tables. They have to maintain an entry in the table
for every router in the network, on every router in the network. The
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effort to create and maintain these static tables grows with the
total number of routers on the network. Changing the name or
systemID of one router, or adding one new router introduced will
affect the configurations of all the other routers on the network.
This will make it very likely that those static tables are outdated.
Having one table that can be updated in a centralized place would be
helpful. One could imagine using the DNS system for this. A drawback
is that during the time of network problems, the response time of DNS
services might not be satisfactory or the DNS services might not even
be available. Another possible drawback might be the added complexity
of DNS. Also, some DNS implementations might not support A and PTR
records for CLNS NSAPs.
A third way to build dynamic mappings would be to use the transport
mechanism of the routing protocol itself to advertise symbolic names
in IS-IS link-state PDUs. This document defines a new TLV which
allows the IS-IS routers to include the name-to-systemID mapping data
in their LSPs. This will allow simple and reliable transport of name
mapping information across the IS-IS network.
3. Dynamic Hostname TLV
The Dynamic hostname TLV is defined here as TLV type 137.
LENGTH - total length of the value field.
VALUE - a string of 1 to 255 bytes.
The Dynamic hostname TLV is optional. This TLV may be present in any
fragment of a non-pseudo node LSP. The value field identifies the
symbolic name of the router originating the LSP. This symbolic name
can be the FQDN for the router, it can be a subset of the FQDN or any
string operators want to use for the router. The use of FQDN or a
subset of it is strongly recommended. The content of this value is a
domain name, see [RFC 2181]. The string is not null-terminated. The
systemID of this router can be derived from the LSP identifier.
If this TLV is present in a pseudo node LSP, then it SHOULD NOT be
interpreted as the DNS hostname of the router.
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4. Implementation
The Dynamic Hostname TLV is optional. When originating an LSP, a
router may decide to include this TLV in its LSP. Upon receipt of an
LSP with the dynamic hostname TLV, a router may decide to ignore this
TLV, or to install the symbolic name and systemID in its hostname
mapping table for the IS-IS network.
A router may also optionally insert this TLV in it's pseudo node LSP
for the association of a symbolic name to a local LAN.
5. Security Considerations
This document raises no new security issues for IS-IS.
6. Acknowledgments
The original efforts and corresponding acknowledgements provided in
[RFC 2763] have enabled this work. In particular, we'd like to
acknowledge Henk Smit as an author of that document.
Others to be provided....
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7. IANA Considerations
This document specificies TLV 137, "Dynamic Name". This TLV has
already been allocated and reserved [RFC 2763]. As such, no new
actions are required on the part of IANA.
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8. References
8.1. Normative References
[ISO 8473] ISO, "Intermediate system to Intermediate system
routeing information exchange protocol for use in conjunction
with the Protocol for providing the Connectionless-mode Network
Service (ISO 8473)," ISO/IEC 10589:1992.
8.2. Informative References
[RFC 2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", RFC 2119, March 1997.
[RFC 2181] Elz, R., Bush, R., "Clarifications to the DNS
Specification", RFC 2181, July 1997.
[RFC 2763] Smit, H., Shen, N., "Dynamic Hostname Exchange
Mechanism for IS-IS, RFC 2763, February 2000.
9. Authors' Addresses
Danny McPherson
Arbor Networks, Inc.
EMail: danny@arbor.net
Naiming Shen
Cisco Systems, Inc.
EMail: naiming@cisco.com
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